It is known to mount solid state light sources, such as semiconductor light emitting diodes (LEDs), in packages that may provide protection, color selection, focusing, and the like, for light emitted by the light emitting diode. A solid state light emitting diode may be, for example, an organic or inorganic light emitting diode. Some packages for light emitting diodes are described in U.S. Pre-grant Publication Nos. 2004/0079957, 2004/0126913, 2005/0269587, and 2008/0012036, which are assigned to the assignee of the present invention, and which are incorporated herein by reference as if set forth fully herein.
According to FIGS. 1A and 1B, a typical leadframe-based LED package 160 includes electrical leads, contacts or traces for electrically connecting the LED package to an external circuit. The package 160 can include a leadframe 102 and a molded package body 130 surrounding the leadframe 102 and a lens 140 mounted over a central region of the leadframe 102. Electrical leads 104, 106 extend from sides of the package body 130. Other optical features, such as reflectors, diffusers, etc., may be provided instead of or in addition to the lens 140.
The package body 130 may be formed of, for example, thermoset and/or a thermoplastic by transfer or injection molding, around the leadframe 102. The thermoplastic may include a liquid crystal polymer such as a Vectra® series polymers A130 and/or S135 available from Ticona Engineering Polymers. Other suitable liquid crystal polymers are available from Solvay Advanced Polymers. Polycarbonate, Lexan® from GE Polymers and/or PPA (polyphthalamide) from Solvay Advanced Polymers may also be used as the thermoplastic for the package body 130.
The package body 130 may expose the bottom surface of the central region of the leadframe 102 and may extend at least partially between lower surfaces 104b, 106b of the leads 104, 106 and a lower surface 102b of the central region of the leadframe 100 while exposing at least a portion of the lower surface 102b of the central region. Further, the package body 130 may have a bottom surface 130b that is coplanar with the bottom surface 102b of the central region of the leadframe 102. When the package 160 is mounted, the exposed surface 102b of the leadframe 102 may be placed into thermal contact with, for example, an external heatsink (not shown).
Other packages, as illustrated in FIG. 2, can include the leadframe 102 supporting a ceramic submount 101 with LEDs 103 thereon. A glass lens 140 can be mounted over the LEDs 103 and a reflector may be provided as part of the package. The LEDs 103 can be electrically connected to the leads 104, 106 by wires 150. Still other packages can include a silicon lens that is injection molded on the submount 101.